1. Field
The present disclosure relates to a stick with a cam lever type locking device, and more particularly, to a stick with a cam lever type locking device capable of preventing a decrease in the locking force exerted when the stick is normally used by preventing the plastic deformation of an engagement portion in a manner such that the locking force applied to the engagement portion of the locking device is decreased when the stick is accommodated in a shortened state for a long period of time.
2. Description of the Related Art
In general, a stick is used as assisting means for supporting a body of a user, for example, in the case of climbing, sport games, or walking of a patient. Such a stick has a configuration in which a handle is provided in the end portion of a pole shaft. The pole shaft is generally configured by inserting and connecting plural connection tubes to each other, whereby the pole shaft may be shortened or lengthened in a so-called ‘telescopic type’ or an ‘antenna type’ when the pole shaft is accommodated and used.
Among locking devices which fix the stick in a lengthened state or a shortened state, there is a known cam lever type locking device having a configuration in which a stick is locked by allowing an engagement portion to pressurize and grip the outer periphery of a connection tube with the operation of a cam lever, which may be conveniently operated by a woman or an aged person.
FIG. 1 is a diagram illustrating an example of a stick which adopts such a locking device.
In FIG. 1, the stick includes plural connection tubes 2, 4, 6, . . . , where among the adjacent connection tubes, the connection tube having a large diameter is referred to as an ‘upper connection tube’ and the connection tube having a small diameter is referred to as a ‘lower connection tube’.
A cam lever type locking device 10 is applied to at least one or more points of the connection portions of the adjacent connection tubes 2, 4, 6 . . . and a general button type locking device 12 is used together. At the time of applying the button type locking device 12, a sleeve 4a is installed at the front end portion of the upper connection tube 4.
Referring to FIG. 1, the connection tube includes three stages of connection tubes. The cam lever type locking device 10 is applied to the first-stage upper connection tubes 2 and the second-stage lower connection tube 4, and the button type locking device 12 is applied to the second-stage upper connection tube 4 and the third-stage lower connection tube 6. Alternatively, the cam lever type locking device 10 may be applied to all of the first-stage and second-stage connection tubes and the second-stage and third-stage connection tubes.
FIG. 2 illustrates an example of the cam lever type locking device.
In the cam lever type locking device 10 shown in FIG. 2, a gripping tube 20 is fixed to the end portion of the upper connection tube 2 having a large diameter, and a tightening plate 24 extends to a portion where a part of the front end portion of the gripping tube 20 is cut as a cut portion 22. A cam lever 40 is installed in the tightening plate 24 through an operation pin 30 and a hinge pin 50. When the cam lever 40 is pressed downward, the cam surface 42 of the cam lever 40 pulls two tightening plates 24, so that a circular-arc engagement portion 23 of the gripping tube 20 pressurizes and grips the outer periphery of the lower connection tube 4.
Further, FIG. 3 illustrates another example of the cam lever type locking device.
In a cam lever type locking device 100 shown in FIG. 3, a gripping tube 120 is fixed to the end portion of the upper connection tube 2 having a large diameter. A cam lever 140 is installed through an operation pin 130 and a hinge pin 150 by cutting both sides of the front end portion of the gripping tube 120 as a cut portion 122. When the cam lever 140 is pressed downward so as to rotate a cam surface 142, two circular-arc engagement portions 123 are tightened so as to pressurize and grip the outer periphery of the lower connection tube 4.
Incidentally, even in a case where the stick is accommodated in a shortened state, the lower connection tube needs to be fixed so as not to be separated by pressing the cam lever 40, 140. That is, the lower connection tube 4 is pressed into the upper connection tube 2 until the sleeve 4a (see FIG. 1) of the front end of the lower connection tube 4 contacts the front end of the upper connection tube 2, and then the cam lever 40, 140 is pressed so as to fix the lower connection tube 4 (see FIG. 1) in a pressurized and gripped state.
Accordingly, during a time in which the stick is accommodated, the engagement portion 23, 123 of the gripping tube 20, 120 pressurizes the outer periphery of the lower connection tube 4. The gripping tube 20, 120 is formed of metal or plastic, and especially in the case of plastic, when the state in which the gripping tube 20, 120 pressurizes and fixes the lower connection tube 4 is maintained for a long period of time, the engagement portion 23, 123 which receives a reaction force undergoes plastic deformation. That is, the circular-arc portion of the engagement portion is stretched. Such plastic deformation may decrease the locking force of the stick, so that a problem arises in that the lower connection tube 4 enters into the upper connection tube 2 when pressing the stick against the ground.